The present invention relates to an ink jet recording sheet, in particular the one usable as pressure-sensitive or quick stick labels, that controls ink dots spread upon being printed by an ink jet printer using an aqueous ink and can develop color images of favorable sharpness and color quality.
The ink jet recording method performs recording of graphics and characters by depositing ink droplets ejected by various working principles on a recording sheet such as paper. Ink jet recording has such favorable features that it makes high-speed recording possible, that it produces little noise, that it can easily perform multi-color recording, that there is no limitation as to the kind of patterns or images, and that it requires no processing for development and fixing. Thus, ink jet recording is rapidly becoming widespread in various fields as devices for recording various characters including kanjis (Chinese characters) and color images. Furthermore, the images formed by the multi-color ink jet recording method are by no means inferior to those printed by a multi-color press or those obtained by color photography. Besides, the use of ink jet recording extends to a field of full-color image recording where number of copies is not so many, since costs per copy are less than those employing the photographic process.
Fields of use of ink jet recording has diversified and one of such fields of note is pressure-sensitive or quick stick labels. The labels such as those for price tags, for optical recognition tags (bar code), and for advertisement (stickers) are being increasingly used. Bar code prints should have a high degree of sharpness and an ink jet printed image can meet this requirement if ink dots spread is controlled. An advantage of the ink jet printed label is that it afford to print color image with a bar code at a corner. A label that prints a color message and a bar code of high sharpness and color quality could have significant promotion effect of a merchandise to which it is put. Another reason to support proliferation of ink jet printed color labels is that a reasonably good image can be drawn and printed by relatively simple devices like a personal computer and printer. Quick stick labels are used widely since they adhere easily to a variety of objects, and their use on an ink jet printer is gradually expanding where merits of both the labels and ink jet printing are combined. However, such favorable combination would not be of significance unless the image printed on the label is as good in image and color reproducibility as the same image printed on a normal ink jet recording sheet.
When an ordinary ink jet recording sheet is processed into a pressure-sensitive label by providing a tacky layer on the back, the ink tends to spread more than needed or even bleed on the surface, so that the record formed lacks the sharpness required for bar code, and the color quality and image reproducibility required for promotion of a merchandise. Improvements have been attempted on coating composition of ink-receiving layer, but any of them has failed so far to show a promise. Accordingly, ink jet recording sheets which inhibit spread of ink dots even when they are processed into pressure-sensitive labels are required. In the current imaging-oriented society, the demand for inhibition of ink dots spread has grown considerably severer.